Sulaim Ibn Qais: O Amirul Mumineen, please tell me the names (of Allah’s Proofs).
He (a.s.) informed: These are those people whom Allah has made close to Him and His Prophet (s.a.w.a.) and He says: Obey Allah and obey the Apostle and those in authority from among you. (Surah Nisa (59): 4)
Sulaim said: Inform me in detail about them.
Ali (a.s.) said: These are the people for whom the Holy Prophet (s.a.w.a.) in his last sermon, after which he passed away said – I leave two things for you – until you are with them you will not deviate – Allah’s Book and my Ahle Bait (a.s.). Because Allah
the Great, the Subtle, has promised me that these two will not separate from each other until they come to me like this (showing his one forefinger touching the forefinger of the other hand) to the fountain of Kausar, because in this (showing two fingers of the same hand) one is shorter than the other. You abide by these two and you will not deviate, and do not go ahead of them otherwise you will be destroyed.
Al-Kaafi v 2 p 415-416, v 4 p 198 Kitaab Sulaym Ibn Qais v 2 p 616